This core has the world's largest collection of well-characterized cases of skeletal dysplasias from which a large bank of clinical information, radiographs, fixed and frozen chondroosseous tissues, cultured fibroblasts and chondrocytes, lymphoblastoid lines and banked DNA are available for clinical, morphological, biochemical, cell physiologic and molecular studies. The Registry will provide cases and biological materials to each of the four research projects in this Program Project.